Monitors are used to monitor all sorts of variables to look for the occurrence of certain noteworthy events. Many actions taken by a subject can generate events that generate data that looks like an alarm, but is merely an artifact. For instance, if a patient moves around, a sensor attached to the patient may generate a data signal that would be indicative of an abnormal condition. This false positive result (registering that an event has occurred when in fact no significant event has occurred) would preferably not result in an alarm being generated. It would be desirable to have a monitor that can indicate when an event has occurred where most of the indicated events are significant. It would also be desirable to avoid registering false positives, while avoiding false negatives (not registering the occurrence of a significant event).
Many subjects, such as patients, differ from each other in many respects that are material to monitoring. For instance, a typical person may have a normal systolic blood pressure of 120, whereas an individual's normal systolic blood pressure may be closer to 100. Some values of a systolic blood pressure may be reasonable for the typical person where they would not be as reasonable for the individual. A monitor that could use limits based on the characteristics of the subject, including typical values for the subject, would be preferable. A monitor that could use limits based on the historical characteristics of a subject would be desirable.
Additionally, readings from a patient may go from a high point in a range that is not alarming for a subject to a low point in the range that is also not alarming. While the values themselves may not be very alarming, the change in value may be significant. For instance, a value that is steadily dropping may be indicative of a problem that is gradually worsening. Also, a value that drops quickly may be a sign that something has gone wrong, even if the value remains in a normal range for the subject. A system that can indicate when the readings are fluctuating, when such fluctuation is important, would be preferable. A system that can identify a relevant event indicated by the fact that the readings are changing over longer periods of time would be desirable.
The teachings herein below extend to those embodiments which fall within the scope of the appended claims, regardless of whether they accomplish one or more of the above-mentioned needs.